3 * DEBUG: section 20 Storage Manager Swapout Functions
4 * AUTHOR: Duane Wessels
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36 #include "StoreClient.h"
39 /* FIXME: Abstract the use of this more */
41 #include "MemObject.h"
42 #include "SquidConfig.h"
44 #include "StatCounters.h"
45 #include "store_log.h"
46 #include "swap_log_op.h"
48 static void storeSwapOutStart(StoreEntry
* e
);
49 static StoreIOState::STIOCB storeSwapOutFileClosed
;
50 static StoreIOState::STFNCB storeSwapOutFileNotify
;
52 // wrapper to cross C/C++ ABI boundary. xfree is extern "C" for libraries.
53 static void xfree_cppwrapper(void *x
)
58 /* start swapping object to disk */
60 storeSwapOutStart(StoreEntry
* e
)
62 MemObject
*mem
= e
->mem_obj
;
63 StoreIOState::Pointer sio
;
65 /* Build the swap metadata, so the filesystem will know how much
66 * metadata there is to store
68 debugs(20, 5, "storeSwapOutStart: Begin SwapOut '" << e
->url() << "' to dirno " <<
69 e
->swap_dirn
<< ", fileno " << std::hex
<< std::setw(8) << std::setfill('0') <<
70 std::uppercase
<< e
->swap_filen
);
71 e
->swap_status
= SWAPOUT_WRITING
;
72 /* If we start swapping out objects with OutOfBand Metadata,
73 * then this code needs changing
76 /* TODO: make some sort of data,size refcounted immutable buffer
77 * and stop fooling ourselves with "const char*" buffers.
80 // Create metadata now, possibly in vain: storeCreate needs swap_hdr_sz.
81 const char *buf
= e
->getSerialisedMetaData ();
84 /* Create the swap file */
85 generic_cbdata
*c
= new generic_cbdata(e
);
86 sio
= storeCreate(e
, storeSwapOutFileNotify
, storeSwapOutFileClosed
, c
);
89 e
->swap_status
= SWAPOUT_NONE
;
90 mem
->swapout
.decision
= MemObject::SwapOut::swImpossible
;
93 storeLog(STORE_LOG_SWAPOUTFAIL
, e
);
97 mem
->swapout
.sio
= sio
;
98 /* Don't lock until after create, or the replacement
99 * code might get confused */
102 /* Pick up the file number if it was assigned immediately */
103 e
->swap_filen
= mem
->swapout
.sio
->swap_filen
;
105 e
->swap_dirn
= mem
->swapout
.sio
->swap_dirn
;
107 /* write out the swap metadata */
108 storeIOWrite(mem
->swapout
.sio
, buf
, mem
->swap_hdr_sz
, 0, xfree_cppwrapper
);
112 storeSwapOutFileNotify(void *data
, int errflag
, StoreIOState::Pointer self
)
114 generic_cbdata
*c
= (generic_cbdata
*)data
;
115 StoreEntry
*e
= (StoreEntry
*)c
->data
;
116 MemObject
*mem
= e
->mem_obj
;
117 assert(e
->swap_status
== SWAPOUT_WRITING
);
119 assert(mem
->swapout
.sio
== self
);
120 assert(errflag
== 0);
121 assert(e
->swap_filen
< 0); // if this fails, call SwapDir::disconnect(e)
122 e
->swap_filen
= mem
->swapout
.sio
->swap_filen
;
123 e
->swap_dirn
= mem
->swapout
.sio
->swap_dirn
;
127 doPages(StoreEntry
*anEntry
)
129 MemObject
*mem
= anEntry
->mem_obj
;
132 // find the page containing the first byte we have not swapped out yet
134 mem
->data_hdr
.getBlockContainingLocation(mem
->swapout
.queue_offset
);
137 break; // wait for more data to become available
139 // memNodeWriteComplete() and absence of buffer offset math below
140 // imply that we always write from the very beginning of the page
141 assert(page
->start() == mem
->swapout
.queue_offset
);
144 * Get the length of this buffer. We are assuming(!) that the buffer
145 * length won't change on this buffer, or things are going to be very
146 * strange. I think that after the copy to a buffer is done, the buffer
147 * size should stay fixed regardless so that this code isn't confused,
148 * but we can look at this at a later date or whenever the code results
149 * in bad swapouts, whichever happens first. :-)
151 ssize_t swap_buf_len
= page
->nodeBuffer
.length
;
153 debugs(20, 3, "storeSwapOut: swap_buf_len = " << swap_buf_len
);
155 assert(swap_buf_len
> 0);
157 debugs(20, 3, "storeSwapOut: swapping out " << swap_buf_len
<< " bytes from " << mem
->swapout
.queue_offset
);
159 mem
->swapout
.queue_offset
+= swap_buf_len
;
161 // Quit if write() fails. Sio is going to call our callback, and that
162 // will cleanup, but, depending on the fs, that call may be async.
163 const bool ok
= mem
->swapout
.sio
->write(
164 mem
->data_hdr
.NodeGet(page
),
167 memNodeWriteComplete
);
169 if (!ok
|| anEntry
->swap_status
!= SWAPOUT_WRITING
)
172 int64_t swapout_size
= mem
->endOffset() - mem
->swapout
.queue_offset
;
174 if (anEntry
->store_status
== STORE_PENDING
)
175 if (swapout_size
< SM_PAGE_SIZE
)
178 if (swapout_size
<= 0)
182 // either wait for more data or call swapOutFileClose()
186 /* This routine is called every time data is sent to the client side.
187 * It's overhead is therefor, significant.
190 StoreEntry::swapOut()
195 // this flag may change so we must check even if we are swappingOut
196 if (EBIT_TEST(flags
, ENTRY_ABORTED
)) {
197 assert(EBIT_TEST(flags
, RELEASE_REQUEST
));
198 // StoreEntry::abort() already closed the swap out file, if any
199 // no trimming: data producer must stop production if ENTRY_ABORTED
203 const bool weAreOrMayBeSwappingOut
= swappingOut() || mayStartSwapOut();
205 Store::Root().maybeTrimMemory(*this, weAreOrMayBeSwappingOut
);
207 if (mem_obj
->swapout
.decision
!= MemObject::SwapOut::swPossible
)
208 return; // nothing else to do
210 // Aborted entries have STORE_OK, but swapoutPossible rejects them. Thus,
211 // store_status == STORE_OK below means we got everything we wanted.
213 debugs(20, 7, HERE
<< "storeSwapOut: mem->inmem_lo = " << mem_obj
->inmem_lo
);
214 debugs(20, 7, HERE
<< "storeSwapOut: mem->endOffset() = " << mem_obj
->endOffset());
215 debugs(20, 7, HERE
<< "storeSwapOut: swapout.queue_offset = " << mem_obj
->swapout
.queue_offset
);
217 if (mem_obj
->swapout
.sio
!= NULL
)
218 debugs(20, 7, "storeSwapOut: storeOffset() = " << mem_obj
->swapout
.sio
->offset() );
220 int64_t const lowest_offset
= mem_obj
->lowestMemReaderOffset();
222 debugs(20, 7, HERE
<< "storeSwapOut: lowest_offset = " << lowest_offset
);
224 #if SIZEOF_OFF_T <= 4
226 if (mem_obj
->endOffset() > 0x7FFF0000) {
227 debugs(20, DBG_CRITICAL
, "WARNING: preventing off_t overflow for " << url());
233 if (swap_status
== SWAPOUT_WRITING
)
234 assert(mem_obj
->inmem_lo
<= mem_obj
->objectBytesOnDisk() );
236 // buffered bytes we have not swapped out yet
237 const int64_t swapout_maxsize
= mem_obj
->availableForSwapOut();
238 assert(swapout_maxsize
>= 0);
239 debugs(20, 7, "storeSwapOut: swapout_size = " << swapout_maxsize
);
241 if (swapout_maxsize
== 0) { // swapped everything we got
242 if (store_status
== STORE_OK
) { // got everything we wanted
243 assert(mem_obj
->object_sz
>= 0);
244 swapOutFileClose(StoreIOState::wroteAll
);
246 // else need more data to swap out
250 if (store_status
== STORE_PENDING
) {
251 /* wait for a full block to write */
253 if (swapout_maxsize
< SM_PAGE_SIZE
)
257 * Wait until we are below the disk FD limit, only if the
258 * next server-side read won't be deferred.
260 if (storeTooManyDiskFilesOpen() && !checkDeferRead(-1))
264 /* Ok, we have stuff to swap out. Is there a swapout.sio open? */
265 if (swap_status
== SWAPOUT_NONE
) {
266 assert(mem_obj
->swapout
.sio
== NULL
);
267 assert(mem_obj
->inmem_lo
== 0);
268 storeSwapOutStart(this); // sets SwapOut::swImpossible on failures
271 if (mem_obj
->swapout
.sio
== NULL
)
275 /* oops, we're not swapping out any more */
278 if (store_status
== STORE_OK
) {
280 * If the state is STORE_OK, then all data must have been given
281 * to the filesystem at this point because storeSwapOut() is
282 * not going to be called again for this entry.
284 assert(mem_obj
->object_sz
>= 0);
285 assert(mem_obj
->endOffset() == mem_obj
->swapout
.queue_offset
);
286 swapOutFileClose(StoreIOState::wroteAll
);
291 StoreEntry::swapOutFileClose(int how
)
293 assert(mem_obj
!= NULL
);
294 debugs(20, 3, "storeSwapOutFileClose: " << getMD5Text() << " how=" << how
);
295 debugs(20, 3, "storeSwapOutFileClose: sio = " << mem_obj
->swapout
.sio
.getRaw());
297 if (mem_obj
->swapout
.sio
== NULL
)
300 storeClose(mem_obj
->swapout
.sio
, how
);
304 storeSwapOutFileClosed(void *data
, int errflag
, StoreIOState::Pointer self
)
306 generic_cbdata
*c
= (generic_cbdata
*)data
;
307 StoreEntry
*e
= (StoreEntry
*)c
->data
;
308 MemObject
*mem
= e
->mem_obj
;
309 assert(mem
->swapout
.sio
== self
);
310 assert(e
->swap_status
== SWAPOUT_WRITING
);
313 // if object_size is still unknown, the entry was probably aborted
314 if (errflag
|| e
->objectLen() < 0) {
315 debugs(20, 2, "storeSwapOutFileClosed: dirno " << e
->swap_dirn
<< ", swapfile " <<
316 std::hex
<< std::setw(8) << std::setfill('0') << std::uppercase
<<
317 e
->swap_filen
<< ", errflag=" << errflag
);
319 if (errflag
== DISK_NO_SPACE_LEFT
) {
320 /* FIXME: this should be handle by the link from store IO to
321 * Store, rather than being a top level API call.
323 e
->store()->diskFull();
327 if (e
->swap_filen
>= 0)
330 assert(e
->swap_status
== SWAPOUT_NONE
);
334 /* swapping complete */
335 debugs(20, 3, "storeSwapOutFileClosed: SwapOut complete: '" << e
->url() << "' to " <<
336 e
->swap_dirn
<< ", " << std::hex
<< std::setw(8) << std::setfill('0') <<
337 std::uppercase
<< e
->swap_filen
);
338 debugs(20, 5, HERE
<< "swap_file_sz = " <<
339 e
->objectLen() << " + " << mem
->swap_hdr_sz
);
341 e
->swap_file_sz
= e
->objectLen() + mem
->swap_hdr_sz
;
342 e
->swap_status
= SWAPOUT_DONE
;
343 e
->store()->swappedOut(*e
);
345 // XXX: For some Stores, it is pointless to re-check cachability here
346 // and it leads to double counts in store_check_cachable_hist. We need
347 // another way to signal a completed but failed swapout. Or, better,
348 // each Store should handle its own logging and LOG state setting.
349 if (e
->checkCachable()) {
350 storeLog(STORE_LOG_SWAPOUT
, e
);
351 storeDirSwapLog(e
, SWAP_LOG_ADD
);
354 ++statCounter
.swap
.outs
;
357 debugs(20, 3, "storeSwapOutFileClosed: " << __FILE__
<< ":" << __LINE__
);
358 mem
->swapout
.sio
= NULL
;
363 StoreEntry::mayStartSwapOut()
365 // must be checked in the caller
366 assert(!EBIT_TEST(flags
, ENTRY_ABORTED
));
367 assert(!swappingOut());
369 if (!Config
.cacheSwap
.n_configured
)
373 MemObject::SwapOut::Decision
&decision
= mem_obj
->swapout
.decision
;
375 // if we decided that swapout is not possible, do not repeat same checks
376 if (decision
== MemObject::SwapOut::swImpossible
) {
377 debugs(20, 3, HERE
<< " already rejected");
381 // if we decided that swapout is possible, do not repeat same checks
382 if (decision
== MemObject::SwapOut::swPossible
) {
383 debugs(20, 3, HERE
<< "already allowed");
387 // if we swapped out already, do not start over
388 if (swap_status
== SWAPOUT_DONE
) {
389 debugs(20, 3, HERE
<< "already did");
390 decision
= MemObject::SwapOut::swImpossible
;
394 if (!checkCachable()) {
395 debugs(20, 3, HERE
<< "not cachable");
396 decision
= MemObject::SwapOut::swImpossible
;
400 if (EBIT_TEST(flags
, ENTRY_SPECIAL
)) {
401 debugs(20, 3, HERE
<< url() << " SPECIAL");
402 decision
= MemObject::SwapOut::swImpossible
;
406 if (mem_obj
->inmem_lo
> 0) {
407 debugs(20, 3, "storeSwapOut: (inmem_lo > 0) imem_lo:" << mem_obj
->inmem_lo
);
408 decision
= MemObject::SwapOut::swImpossible
;
412 if (!mem_obj
->isContiguous()) {
413 debugs(20, 3, "storeSwapOut: not Contiguous");
414 decision
= MemObject::SwapOut::swImpossible
;
418 // check cache_dir max-size limit if all cache_dirs have it
419 if (store_maxobjsize
>= 0) {
420 // TODO: add estimated store metadata size to be conservative
422 // use guaranteed maximum if it is known
423 const int64_t expectedEnd
= mem_obj
->expectedReplySize();
424 debugs(20, 7, HERE
<< "expectedEnd = " << expectedEnd
);
425 if (expectedEnd
> store_maxobjsize
) {
426 debugs(20, 3, HERE
<< "will not fit: " << expectedEnd
<<
427 " > " << store_maxobjsize
);
428 decision
= MemObject::SwapOut::swImpossible
;
429 return false; // known to outgrow the limit eventually
432 // use current minimum (always known)
433 const int64_t currentEnd
= mem_obj
->endOffset();
434 if (currentEnd
> store_maxobjsize
) {
435 debugs(20, 3, HERE
<< "does not fit: " << currentEnd
<<
436 " > " << store_maxobjsize
);
437 decision
= MemObject::SwapOut::swImpossible
;
438 return false; // already does not fit and may only get bigger
441 // prevent final default swPossible answer for yet unknown length
442 if (expectedEnd
< 0 && store_status
!= STORE_OK
) {
443 const int64_t maxKnownSize
= mem_obj
->availableForSwapOut();
444 debugs(20, 7, HERE
<< "maxKnownSize= " << maxKnownSize
);
446 * NOTE: the store_maxobjsize here is the global maximum
447 * size of object cacheable in any of Squid cache stores
448 * both disk and memory stores.
450 * However, I am worried that this
451 * deferance may consume a lot of memory in some cases.
452 * Should we add an option to limit this memory consumption?
454 debugs(20, 5, HERE
<< "Deferring swapout start for " <<
455 (store_maxobjsize
- maxKnownSize
) << " bytes");
456 return true; // may still fit, but no final decision yet
460 decision
= MemObject::SwapOut::swPossible
;